A U.S. strike aircraft shot down a Syrian government fighter jet shortly after it bombed U.S.-backed Syrian fighters in North Syria, the Pentagon said in a statement Sunday.

The Pentagon said the shoot-down came hours after Syrian government-backed forces attacked U.S.-backed fighters, known as the Syrian Democratic Forces, in the village of Ja'Din. As the attack unfolded, the U.S. military used a deconfliction channel to communicate with the Syrian government to stop the skirmish, according to the Pentagon statement.

U.S.-led jets stopped the fighting by flying close to the ground and at low-speed in what is called a "show of force," the Pentagon said.

Roughly two hours later, despite the called-for stand down and the U.S. presence overhead, a Syrian Su-22 jet attacked the Syrian Democratic Forces, dropping an unknown number of munitions on the U.S.-backed force. A U.S. F/A-18 promptly shot the Syrian aircraft down "in accordance with rules of engagement and in collective self-defense of coalition partnered forces," the Pentagon statement said.

A statement distributed by the Syrian military and distributed on Twitter said that the aircraft's lone pilot was killed in the attack.

"The attack stresses coordination between the US and ISIS, and it reveals the evil intentions of the US in administrating terrorism and investing it to pass the US-Zionist project in the region," the Syrian statement said, using an acronym for the Islamic State.

The incident marks the first time a U.S. jet has shot down a manned hostile aircraft in more than a decade, and is a marked escalation in the six-year-old Syrian conflict.

Earlier this month, a U.S. jet downed a pro-Syrian government drone that dropped an apparent dud munition near U.S.-led coalition forces near the southern Syrian town of At Tanf. U.S.-led forces have increased their presence at Tanf to deter pro-Syrian government forces in the area. Iran-backed Shiite militias, along with other pro-Syrian government forces have steadily advanced around Tanf despite repeated warnings from the U.S. military.